Stirling-Type Pulse Tube Cryocooler With 1kw of Refrigeration at 77k

Abstract. Callaghan Innovation has been developing a metal-diaphragm pressure wave generator technology for pulse tube or Stirling cryocoolers since 2005. A series of successful pressure wave generators have been designed, fabricated and demonstrated ranging in swept volume from 20 to 240 cc driven by commercially available induction motors of powers from 0.5 kW to 7.5 kW respectively. A number of pulse tubes have also been design and successfully trialed with these pressure wave generators. Cooling powers up to 600 W at 120 K have been achieved. We have now scaled the pressure wave generator technology to 1000cc swept volume, powered by a 30 kW induction motor with the intention of providing over 20 kW of acoustic power to either pulse tube or Stirling expanders. The aim is to develop a cryocooler with more than 1000 W of refrigeration at 77 K. Target applications include liquefaction and High Temperature Superconducting devices. Initial results from testing the 1000 cc pressure wave generator are presented and we will discuss the challenges and advantages involved in scaling the metal diaphragm technology to higher acoustic powers.

Section: Advances In Cryogenic Engineeringmentioning

confidence: 99%

“…The goal of this exercise was to produce a PWG for a cryocooler with over 1 kW cooling at 77 K. To determine a suitable swept volume we considered Praxair's 1 kW pulse tube [9] which used a linear PWG that developed 18.5 kW of P-V power to achieve 1100 W of cooling at 80 K.…”

Section: Designmentioning

confidence: 99%

30 kW metal diaphragm pressure wave generator

Caughley¹,

Branje²,

Klok³

2014

“…Making the buffer tube have a large area makes its optimum length relatively short, however, to minimize the compressible volume (which must in turn be fed by the inertance tube) and to minimize the surface area for thermoacoustic heat transport. It may seem counterintuitive to make the buffer tube wide and (relatively) short, but this is exactly the design used successfully in hardware described in [1] and [2].…”

Section: Challenges Of Scalementioning

confidence: 99%

“…However, until recently there have been no commercially available PTC's offering capacities above a few tens of watts at 80K, not enough for many of the applications still dominated by Gifford-McMahon coolers and other entrenched technologies. Large capacity, high-efficiency PTC's have been demonstrated [1,2] but the largest are still "in-line" coldheads, with embedded cold heat exchangers. This style of head is the most logical choice for a first demonstration at a new scale, for it is easier to maintain uniform oscillating flows between components, and more readily embodies the 1-dimensional character of simulations (such as DeltaE [3] and Sage [4]).…”

Section: Introductionmentioning

confidence: 99%

Large Coaxial Coldfinger PTC for Process Liquefaction and HTS Applications

Spoor¹,

Corey²,

Weisend³

2010

Self Cite

Large (>100W cooling capacity at 80K) 'pulse-tube' coolers are ideal candidates for emerging applications such as HTS transmission lines, transformers, and motor windings, meso-scale oxygen liquefaction on-demand, cryopumping, and cryogen boiloff recovery. A number of successful large 'in-line' pulse-tube coolers have been built, but these require embedded shell-and-tube process heat exchangers, hence transport of the process fluid/gas to and from the coldhead, and often a high degree of process fluid purity, to avoid clogging in the narrow inlets and outlets of these heat exchangers. It is far preferable in most circumstances to have a coldfinger design that presents a salient cold tip, with the coldhead at the end of a flexible transfer line, as is done with Gifford-McMahon or Joule-Thomson coolers. This paper presents some design details and data from the development of our first high-capacity coldfinger, as well as the results of its application to a 55 gallon/day oxygen liquefier for the Navy.

“…This technology has matured in small cryocoolers for the space, telecommunication or military markets, usually for cooling sensors or electronics. Large linear motor pressure wave generators, over 10kW power, have been made [3] and demonstrated long life and high efficiency. However the need for clean assembly, tight tolerances and power electronics to maintain resonance has kept manufacturing costs high and places limits on potential markets.…”

Section: Introductionmentioning

confidence: 99%

Diaphragm Pressure Wave Generator Developments at Industrial Research LTD

Caughley¹,

Emery²,

Glasson³

et al. 2010

Self Cite

Industrial Research Ltd (IRL) have been developing a unique diaphragm based pressure wave generator technology for pulse tube and Stirling cryocoolers. Our system uses a metal diaphragm to separate the clean cryocooler gas circuit from a conventionally lubricated mechanical driver, thus producing a clean pressure wave with a long life drive that does not require the precision manufacture and associated costs of large linear motors. The first successful diaphragm pressure wave generator produced 3.2kW of acoustic power at an electro-acoustic efficiency of 72% with a swept volume of 200ml and a prototype has now accumulated over 2500 hours running. This paper describes recent developments in the technology. To explore scaling, a small diaphragm pressure wave generator with a swept volume of 20ml has been constructed and has delivered 454W of acoustic power at an electro-acoustic efficiency of 60%. Improvements have been made to the hydraulic force amplifier mechanism for driving the diaphragms resulting in a cheaper and lighter mechanism than the mechanical linkage originally used. To meet a customer's specific requirements, the 200ml pressure wave generator's stroke was extended to achieve 240ml of swept volume thereby increasing its acoustic power delivery to 4.1 kW without compromising efficiency.